C Program to Check Whether a Number is Positive or Negative or Zero

A positive, negative, or zero number can be identified by comparing it with 0. This program uses conditional statements to determine the type of the given number.

• If the number is greater than 0, it is positive.
• If the number is less than 0, it is negative; otherwise, it is zero.

Examples

Input: 10
Output: Positive
Explanation: Since 10 is greater than 0, it is positive.

Input: -5
Output: Negative
Explanation: Since -5 is less than 0, it is negative.

Ways to Check for Positive Numbers, Negative Numbers, or Zero

There are two ways to check whether a given number is positive, negative, or zero:

1. Using Conditional Statements Like if-else

The simplest way to check whether a number is positive, negative, or zero is by using an if-else-if ladder.

• First, check if the number is 0; then check if it is less than 0 (negative).
• If neither condition is true, the number is greater than 0 and is positive.

#include <stdio.h>

void checkNum(int N) {
  
    // Check if the number is zero
    if (N == 0) {
        printf("Zeri\n");
    }
    // Check if the number is less than zero
    else if (N < 0) {
        printf("Negative\n");
    }
    // If neither, the number is positive
    else {
        printf("Positive\n");
    }
}

int main() {
    int N = 10;
    checkNum(N);
    return 0;
}

Positive

2. Using Bitwise Operators

The most significant bit (MSB) of an integer represents its sign in a signed binary representation. A 0 sign bit indicates a positive number, while a 1 sign bit indicates a negative number.

• The MSB can be extracted using bitwise operators to determine whether the number is positive or negative.
• Zero must be checked separately because its sign bit alone cannot distinguish it from a positive number.

#include <stdio.h>

void checkNum(int N) {

    // Check if the number is zero
    if (N == 0) {
        printf("Zero\n");
        return;
    }

    // Extracting msb
    int msb = N & (1 << (sizeof(int) * 8 - 1));

    if (msb)
        printf("Negative\n");
    else
        printf("Positive\n");
}

int main() {
    int N = 10;
    checkNum(N);
    return 0;
}